Author:

Keywords:

Science & Technology, Physical Sciences, Physics, Nuclear, Physics, NEUTRON-RICH ZN, 0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics, Nuclear & Particles Physics, 5106 Nuclear and plasma physics

Abstract:

Isobarically purified beams of 77Cu with energies of 225 and 0.2 MeV were used at the Holifield Radioactive Ion Beam Facility of Oak Ridge National Laboratory to study beta decay into states in 77Zn. Data taken at 225 MeV allowed the determination of absolute branching ratios relative to the decay of 77Cu for this beta decay as well as its daughters. From these we obtained a refined beta-delayed neutron emission probability of 30.3(22)% and a probability that the decay proceeds through 77Zn(g) of 49.1(26)%. A total of 64 gamma rays were placed in a level scheme for 77Zn containing 35 excited states including one state above the neutron separation energy, whereas two gamma rays were observed for the βn branch to states in 76Zn. The growth and decay curves of some prominent gamma rays indicate a single beta-decaying state with a half-life of 480(9) ms. The decay pattern for 77Cu, with observed feeding of 8(3)% to 7/2+ 77Zn(g) and 6(3)% to 1/2− 77Zn(m), in contrast to the large feeding observed for decay of proton-p3/2 73Cu(g) to 1/2− 73Zn(g), strongly suggests a proton-f5/2 ground state for the studied 77Cu activity.